Grow up, Nick Kyrgios told, as he advances to third round of US Open

Nick Kyrgios is set to rocket up the rankings and become Australia's No.1 player after blasting his way into the third round of the US Open in New York.

But coach Todd Larkham has challenged Kyrgios to "act like the No.1" Australia player and the Canberra prodigy got a dressing down from Pat Rafter and Davis Cup coach Josh Eagle about his on-court professionalism.

Kyrgios beat Andreas Seppi 6-4, 7-6 (7-2), 6-4 on Friday morning Australian time in the most emphatic victory of his two-year grand slam career.

He will play Spanish veteran Tommy Robredo for a place in the last 16, but he will almost certainly jump over stalwart Lleyton Hewitt to become Australia's highest-ranked player after the tournament.

A fired-up Kyrgios let his emotions fly in his round-one win against Mikhail Youzhny, picking up three code violations and being one short of disqualification.

But Rafter and Eagle stepped in to help Kyrgios keep a calm head as he continues his captivating grand slam rise.

"The great players don't carry on like he did against Youzhny, but he looked like a professional, top 20 player against Seppi," Larkham said.

"Eagle and Rafter had some good talks to him ... he took that on board. You could see he was more relaxed and he was getting rid of that anger.

"He definitely took on board what they said to him and he was greatly improved; they'll be looking for a similar attitude for the next match.

"We don't know what his ranking will be, but he will be No.1 in Australia. It's a very fast rise, last year he was 20th in Australia. It's a big responsibility and he's got to act like the No.1 as well."

Kyrgios is refusing to put a limit on how far he can advance in the tournament.

World No.18 Robredo is waiting in the next round, which will be played on Monday morning Australian time, and if he wins that the former Daramalan College student will likely square off against world No. 4 and Australian Open champion Stan Wawrinka.

"If I play like I played today, just do whatever I can to recover and keep having fun, I can make an impact," Kyrgios said.

Fans flocked to Court 5 to see tennis's new new Kid Dynamite in action, filling every nook and cranny, and he didn't disappoint, jamming down another 22 aces – taking his tournament tally to 48 in six flawless sets – in the near-two-hour clinic.

Kyrgios didn't drop serve once and said he was pumped to have followed up his giant-killing quarter-final run at Wimbledon – where he took down Rafael Nadal and Richard Gasquet – with a last-32 showing in New York.

"It's always a good feeling to win another match at a grand slam, especially new ground for me," he said.

"[I've] never made it past the first round at the US Open main draw. To have gone to the third round, having beaten some quality opponents, feels good."

Robredo beat Roger Federer at the US Open last year and is the 14th seed this year.

Kyrgios battled a bone stress injury in his left arm before the tournament and had to call a medical timeout against Seppi after complaining of a knee injury.

Larkham is adamant the developing 19-year-old has the physical attributes to last five sets if required in the New York heat.

And the Canberra coach believes his star pupil has the power to topple Robredo and go on another giant-killing run.

"It's definitely a winnable match. Tommy is one of the great competitors, but he doesn't have some of the firepower Nick has," Larkham said.

"He makes a lot of balls, but he doesn't have a massive serve. He won't give Nick unforced errors, but to be honest I think it's on Nick's racquet, and his execution will have to be near perfect to beat Robredo."